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Is there any mustard under your oil cap?

5K views 18 replies 7 participants last post by  Alien945 
#1 ·
I have a 1998 E320(V6) and I have to use half a gallon of coolant every 70-100 miles but I do not see any sign of leak from the hoses nor do I see any leak when it's stationary. I've done the oil changes on time so far and the oil is absolutely fine when I drain it. When I remove the oil cap however, I have something like this under:


.
I live in Florida btw. I was wondering if anyone ever notices such thing. I am scared that I might have a blown head gasket but I just want to do all the other things like hoses, radiator, water, etc. first since those have not been changed and the car has 134000 miles.
 

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#6 ·
I have the same, aswell as it seems i need to refill some coolant without seeing a leak. I did recently replace thermostat and coolant, and everytime i check now there is some missing, i wasnt sure since it is normal for it to do this after a r&r.

I have just replaced filter and oil, and it is also winter here with cold starts, but it might be more to the story here.

I am aware that cold starts, short trips can make the same symtpons, but i gonna keep an eye on this, and maybe ask dealership what they think when i get it into to mandatory control in April. Engine runs like a cat, uphil in third or above it doesnt feel that agile tho, at least under 3000 rpm, but it is a heavy car and i dont know if i lack any power. First and second gear the car is strong from 2000 rpm, maybe alittle lower, so i dont know. But interesting if this sympton can have several causes, if i understand correct?
 
#7 ·
i believe you are absolutely correct, ie. the symptom may be caused by different
factors.

i feel that if you're not suffering from any loss in coolant and your trips tend
to be short commutes and the ambient air temperature is cold, the likelihood
is simply that you need to plan your trips and combine errands if possible. this
will give the car ample time to heat up and to generate enough engine heat to
heat the oil sufficiently

if you can confirm that coolant is needing to be added frequently, you're seeing
steam vapor from your exhaust even after the car has been running at the
normal operating temperature for a period. you may have a head gasket
fracture. this is where a simple leakdown test can determine loss of pressure
and verify the neat for a gasket replacement
 
#10 ·
Is a leakdown test the one where they remove spark plugs 1 at the time and pressurise the cylinder?

Anyways yes i must ask the specialist on dealership to help diagnose it. I am close to the mandatory EU inspection, just a few months so if(and i guess from what i read in this thread) i can just keep driving, this is not critical right?
 
#8 ·
That's a lot of fluid loss. A half gallon every 70-100 miles is a lot. You need to do a pressure test on the cooling system. You should also get some leak detecting dye and check everything for leakes. You can also get your coolant and oil sent out and analyzed for very cheap and sometimes even for free. Just because the oil looks fine doesn't mean there isnt coolant in the oil.

The head gasket isn't normally something that fails on these engines but it's still possible. There's also many things to check, and just because you don't see any signs of a leak, doesn't mean it's automatically something very expensive or difficult to fix. Could be leaking from a hose that isn't very visible, possibly the washer fluid heating system, heater core, or head gasket.

The leak also might not be visible when the engine is off since there's no pressure but with the engine at operating temp and pressurized the leak may show itself.
 
#9 ·
i had a truck which was losing coolant. upon casual inspection (steam, visible
leaks, exam of oil, etc) everything appeared fine. I owned the truck for 10
years so I knew the pulse of it's health and operation. so i asked them to
pressure test the cooling system. sure enough....baaarely detectable was a
loss of pressure. having determined that it wasn't at other junctures such as
hose, pump, etc, I gave them go ahead to pull the top end whereby they found
a hairline fracture in the head gasket.

sometimes it is beyond keyboard guessing and requires more probing and
questions/answers back and forth.
 
#13 ·
Ah yes, i had this feeling since i got the car, not because i owned for alot of time, but i noticed the front window wiper was unusable. And i couldnt put my finger on it, but i noticed the very off looking colour in cooler reservoir, and i noticed the coil in washer reservoir.

Now i have a new wiper and that "film" is always there when i am using my wiper. If i empty the washer tank and fill up then it is ok for a while then the film reappears.

Ok this gonna be a nice spring/summer puzzle, i really liked that video in sticky with the UV light. I might not be able to be as refined, but the washer reservoir and coil gonna be emptied and demounted, aswell as a flushing out the old coolant.
 
#17 ·
While adding coolant the last time, I bought some dye(safe for the coolant that I use) and used it. I found a leak(I don't know if that is where all of it is coming from but there was quite a bit of residue in there.
Auto part Vehicle Engine Car

The leak that I found is coming from the hose attached to the lower metal tube(the one where the arrow is pointing). Does anyone know the part number or the specific name of that part. I am also going to change to upper radiator hose and the thermostat since that was not done the last time I did the coolant change.
 
#18 ·
While adding coolant the last time, I bought some dye(safe for the coolant that I use) and used it. I found a leak(I don't know if that is where all of it is coming from but there was quite a bit of residue in there.
[iurl="http://www.benzworld.org/forums/attachment.php?attachmentid=2105930&d=1488907544"]
[/iurl]
The leak that I found is coming from the hose attached to the lower metal tube(the one where the arrow is pointing). Does anyone know the part number or the specific name of that part. I am also going to change to upper radiator hose and the thermostat since that was not done the last time I did the coolant change.
I believe the hose is called a coolant bypass hose.

https://www.fcpeuro.com/products/mercedes-engine-coolant-by-pass-hose-1122030382

https://www.fcpeuro.com/products/mercedes-engine-coolant-bypass-hose-cooler-to-pump-mer-1122030382
 
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